Corrosion inhibition of aqueous solutions of inorganic mineral acids

ABSTRACT

AQUEOUS SOLUTIONS OF INORGANIC MINERAL ACIDS ARE INHIBITED AGAINST THEIR CORROSIVE TENDENCIES BY THE ADDITION THERETO OF FROM 0.001 TO 2% BY VOLUME OF A COMPOSITION COMPRISING: (A) A MANNICH REACTION CONDENSATION PRODUCT FORMED BY REACTING ONE MOLE OF HYDROABIETYL AMINE WITH TWO MOLES OF FORMALDEHYDE AND TWO MOLES OF AN ALDEHYDE CONTAINING FROM TWO TO SIX CARBON ATOMS AND AT LEAST ONE HYDROGEN ATOM ON THE CARBON ATOM ADJACENT TO THE ALDEHYDIC CARBONYL CARBON ATOM, AND (B) AN ACETYLENIC ALCHOL WHICH CONTAINS THREE TO TWELVE CARBON ATOMS WITH THE RATIO OF A:B BEING WITHIN THE RANGE OF FROM 5:1 TO 1:5.

United States Patent O 3,585,136 CORROSION INHIBITION OF AQUEOUS SOLU- TIONS OF INORGANIC MINERAL ACIDS James R. Stanford, Houston, Tex., assignor to Nalco Chemical Company, Chicago, Ill. N Drawing. Filed Mar. 4, 1968, Ser. No. 709,918 Int. Cl. Clld 7/08 U.S. Cl. 252--8.55 7 Claims ABSTRACT OF THE DISCLOSURE Aqueous solutions of inorganic mineral acids are inhibited against their corrosive tendencies by the addition thereto of from 0.001 to 2% by volume of a composition comprising:

(A) A Mannich reaction condensation product formed by reacting one mole of hydroabietyl amine with two moles of formaldehyde and two moles of an aldehyde containing from two to six carbon atoms and at least one hydrogen atom on the carbon atom adjacent to the aldehydic carbonyl carbon atom, and

(B) An acetylenic alcohol which contains three to twelve carbon atoms with the ratio of A:B being within the range of from 5:1 to 1:5.

INTRODUCTION The present invention is directed to providing inhibited acid solutions whereby their aggressiveness toward ferrous metals is substantially reduced.

Mineral acid solutions are used in numerous industrial applications. They are used in cleaning of metals and in processes wherein they contact a variety of ferrous metals.

A particularly corrosive use of mineral acids is the employment of solutions and, in some instances, even more concentrated solutions of hydrochloric acid in oil well acidizing applications. Due to the excessive temperatures encountered in the lower levels of many oil wells the acid solutions are elevated to excessive temperatures, thereby greatly increasing their corrosiveness to ferrous metals. In such acidizing treatments it is not uncommon for the temperatures of the acid solutions to be raised to between ISO-300 F.

In recent years the art has developed a number of inhibitors in an attempt to reduce the corrosive tendencies of acids such as hydrochloric towards ferrous metals. A common type of inhibitor used either alone or in combination with other chemicals are the acetylenic alcohols such as propargyl alcohol and 4-ethyl-l-octyn-3-ol. The use of this latter alcohol is described in US. 3,249,548.

While the acetylenic alcohols have proven to be of some value in reducing the corrosive tendencies of hydrochloric acid solutions at elevated temperatures, their use is not entirely satisfactory. At effective levels their cost is prohibitive. Also they are not completely effective when the temperature of the acid solutions is in excess of 150 F.

If it were possible to improve the effectiveness of acetylenic alcohols whereby they could be used in small amounts and yet at the same time provide improved corrosion inhibition, a major advance would be afforded to the art.

OBJECTS OF THE INVENTION It therefore becomes an object of the invention to provide improved acetylenic alcohol containing compositions for use in rendering aqueous solutions of inorganic mineral acids noncorrosive.

Another object of the invention is to provide corrosion inhibitors for hydrochloric acid which are effective in ice preventing corrosion of ferrous metals in contact with such solutions whose temperature has been elevated to F. and above.

Other objects will appear hereinafter.

THE INVENTION In accordance with the invention it has been found that aqueous solutions of inorganic mineral acids particularly hydrochloric acid solutions may be inhibited against their corrosive tendencies toward ferrous metals by adding thereto novel compositions of the invention whereby inhibited mineral acid aqueous solutions are pro- Vided.

In its simplest embodiment the invention comprises using in combination the Mannich reaction products of a hydroabietyl amine, formaldehyde, and certain aliphatic aldehydes in combination with an acetylenic alcohol which contains from 3 to 12 carbon atoms.

The Mannich reaction products are combined with the acetylenic alcohols to provide a weight ratio within the range from 5:1 to 1:5. In a preferable embodiment of the invention the weight ratio of Mannich reaction products to acetylenic alcohols is within the range of 3:1 to 1:3 and, most preferably, 1:1 to 1:3.

The compositions of the type described above are added to aqueous solutions of mineral acids to provide on a volume basis from .001 to 2% by volume although, in most instances, dosages between 0.005 to 1% by volume give adequate results. This dosage is based on the volume of the total solution. The invention further contemplates finished corrosion inhibiting compositions utilizing the Mannich reaction products and acetylenic alcohols as described above in combination with oil soluble dispersants having nonionic or anionic characteristics. Such blends are further utilized in combination with an organic solvent-most preferably, a petroleum derived organic solvent such as a highly aromatic petroleum fraction.

When such corrosion inhibiting compositions are employed, they may be combined to provide finished products having the following general compositions as set forth below in General Formula I.

General Formula I Ingredients: Percent by weight Mannich reaction products and acetylenic alcohol (wt. ratio5:l to 1:5) 10-30 Oil soluble dispersant 5-40 Organic solvent Balance MANNICH REACTION PRODUCTS where in the above formula R is a hydroabietyl radical; R and A are radicals from the group consisting of hydrogen and lower aliphatic hydrocarbon groups with the total number of carbon atoms in A+R being not greater than 4.

In order to be capable of entering into the Mannich reaction, the aldehyde must contain at least 1 hydrogen atom on the carbon atom adjacent to the aldehydic carbonyl carbon atom. The Mannish reaction is described in greater detail in Introduction to Organic Chemistry, Condon & Meislich, Holt, Rinehart & Winston, Inc., New York (1961).

ACETYLENIC ALCOHOLS The acetylenic alcohols include those alcohols containing the acetylenic grouping and contain from 3-12 carbon atoms. The preferred alcohols used in the practices of this invention are propargyl alcohol and, most preferably, 4- ethyl-1-octyn-3-ol. Other alcohols suitable for use in preparing the compositions of the invention come within the following structural formula:

n noc czcn wherein R is H, alkyl or phenyl and R is H or lower alkyl.

Alcohols of the above type are set forth in US. 3,049,- 496, the disclosure of which is incorporated herein by reference.

THE OIL SOLUBLE DISPERSANTS The oil soluble dispersants used in preparing finished inhibitor products are most preferably oil soluble or at least oil dispersible. They are either anionic .or non-ionic at use levels. The non-ionic products are prepared by reacting fatty acids, alcohols, alkyl phenols and the like with between 50 moles of either ethylene or propylene oxide.

Preferred chemicals of this type are the alkyl phenols or fatty acids which have been reacted with from between 5-25 moles of ethylene oxide.

Fatty acids per se, e.g. C12-C22 fatty acids, may be used as well as the polymerized diethanoid fatty acids which form dimers and trimers and mixtures thereof upon polymerization. See particularly US. 2,482,761 and 2,763,612. When the fatty acids are used alone it is desirable that they be used as the free acid rather than as their soaps or salts.

The oil soluble dispersants of the types described above when used in preparing corrosion inhibiting compositions tend to improve the operability of the Mannich reaction products in combination with the acetylenic alcohol. They allow the alcohol, particularly the higher alcohols, to be dissolved or dispersed into the mineral acid. They perform a similar function with respect to Mannich reaction products. They are also important in that they provide a better wetting of the inhibitor on the metal surfaces sought to be protected.

THE ORGANIC SOLVENTS Many of the well-known organic solvents can be used to dissolve the above-described ingredients. Preferably these solvents are petroleum base solvents and contain at least by weight of aromatic constituents. Thus, such well-known fractions as aromatic oils, Stoddard solvents, naphthas and the like may be utilized. Generally those aromatic solvents having a boiling point above that of gasoline but below that of lubricating oils are satisfactory.

Other well-known organic solvents that may be used are for instance, benzene, toluene, xylene, dimethylformamide, dimethylsulfoxide and the like.

THE EVALUATION OF THE INVENTION Listed below are typical compositions of the invention; Compositions I through III and IX and X are Mannich reaction products.

EXAMPLE I Composition 1 Gms.

Rosin amine D 1 Muriatic acid (30% HCl) 3O Isopropanol (99%) Formalin (37%) 80 Acetaldehyde 88 1 Hydroabietyl amine.

The above were added to a three necked flask and heated between 60 and 70 C. for 4 hours to yield the finished product.

EXAMPLE II Composition 2 Gms.

Rosin amine D 17 Muriatic acid 6 Isopropanol (99%) 50 Formalin (37%) 8 Acetaldehyde 9 1 Hydroabietyl amine.

The above were added together to a Fisher Pressure bottle in the order listed, sealed and mounted on a revolving wheel at F. for 16 hours.

EXAMPLE III Composition 3 Gms. Rosin amine D 1 9 Muriatic acid 3 Isopropanol 50 Formalin (37%) 8 Acetaldehyde 9 Ilydroabietyl amine.

The above were added together to a Fisher Pressure bottle and mounted on the wheel for 24 hours at 160 F.

Composition 4 Gms. Composition 2 20 Nonyl phenol+l2 moles ethylene oxide 30 Crude tall oil 20 Propargyl alcohol 10 Composition 5 Composition 3 40 Nonyl phenol+l2 moles ethylene oxide 20 Crude tall oil 30 Propargyl alcohol l0 Composition 6 Composition 2 20 Nonyl phenol+l2 moles ethylene oxide 15 Tall oil+15 moles ethylene oxide 15 Crude tall oil 4O Propargyl alcohol 10 Composition 7 Composition 2 30 Nonyl phenol+l2 moles ethylene oxide 15 Tall oil-|-1S moles ethylene oxide 15 Crude tall oil 30 Propargyl alcohol 1O Composition 8 Composition 2 12 Nonyl phenol+l2 moles ethylene oxide 7 Tall oil+15 moles ethylene oxide 8 Crude tall oil 20 Propargyl alcohol 2 EXAMPLE IV Composition 9 Gms. Rosin amine D 1 51 Muriatic acid 18 Isopropanol (99%) 25 Formalin (37%) 24 Acetaldehyde 27 1 Hydroabieltyl amine.

The above was added to a Fisher Pressure bottle and mounted on a revolving wheel at 160 F. for 72 hours.

EXAMPLE V Composition 10 Gms. Rosin amine D 1 34 Muriatic acid 12 Isopropanol (99%) 25 Formalin (37%) 40 Acetaldehyde 40 1 Hydroabietyl amine.

The above were added to a Fisher Pressure bottle and mounted on the wheel for 72 hours.

Composition 11 Gms.

Composition 9 67 Isopropanol (99%) 62 Composition 12 Gms.

Composition 11 30 Aromatic solvent 50 Octynol 2 1O Nonyl phenol-H2 moles ethylene oxide 10 Composition l3 Gms.

Composition 11 20 Tall oil+l5 moles ethylene oxide 15 Nonyl phenol-[-12 moles ethylene oxide 15 Crude tall oil Aromatic solvent 20 Octynol 10' Composition 14 Gms.

Composition 13 80 Polyamine bottoms 20 Composition 1-5 Gms.

Composition 13 80 Dimer and trimer fatty acids-still bottoms 20 Composition 16 Gms.

Composition 13 80 Sulfurized tall oil 20 Composition 17 Gms.

Composition 13 80 Water 16 Composition 18 Gms.

Composition 13 80 Dimer and trimer fatty acids-still bottoms 20 6 Composition 19 Gms. Composition 11 20 Nonyl phenol-H2 moles ethylene oxide 15 Tall oil+15 moles ethylene oxide 15 Aromatic solvent 40 Octynol 5 Aromatic solvent 15 4-ethy1-Loctyn-3-o1.

Composition 20 Gms. Composition 11 30 Aromatic sol-vent 50 Octynol 10 Nonyl phenol+12 moles ethylene oxide 1O 2 4-etliyl-1'octyn-3-o1.

Composition 21 Gms. Composition 9 20 Nonyl phenol+12 moles ethylene oxide 15 Tall oil+15 moles ethylene oxide 15 Crude tall oil 20 Aromatic solvent 20 Octynol 2 10 11 4-ethyl-l-octyn-3-ol.

Composition 22 Gms. Composition 9 10 Tall oil+ 15 moles ethylene oxides 25 Nonyl phenol+ 12 moles ethylene oxide 15 Crude tall oil 20 Aromatic solvent 20 Octynol 2 10 4-ethyl-Loetyn-3-ol.

Composition 23 Gms. Composition 13 KI 5 Water 5 Composition 24 Gms. Composition 13 80 KI 10 Water 10 Composition 27 Gms. Composition 13 45 I-Iydroabietyl amines-i-S moles ethylene oxide+15% hydroabietyl amine CORROSION TESTS In the small scale laboratory tests which follow, three different types of ferrous metal specimens were used:

Specimens (1) High pressure steel tubing-American Petroleum Institute designation N80.

(2) Mild steel coupons SAE 1020 cold rolled steel.

(3) High carbon steel drill rod.

All tests used 15% HCl solutions as the test media.

No blank results are indicated since under the test conditions at temperatures in excess of the test specimens were completely destroyed.

In a series of tests corresponding to those hereinafter described the Mannich reaction products were evaluated and were found to be no better than the blank test results.

4-ethyl-1-octyn-3-ol was evaluated under the test conditions shown and the concentrations used in the test and in all instances gave 50% poorer results than the compositions of the invention.

Results of testing the various compositions of the invention are set forth below in Table I.

TABLE 1 Time, Temp, Specimen (n(-., Wt.

hrs F. ypigal. 1,000 loss, g

6 200 l 4 3. 0062 6 200 1 4 763 6 .300 l 2 1. 5123 6 201] 1 2 .2470 6 200 l 4 0. 5123 5 /2 201] 1 .2 J. 8084 5 200 l 4 U 5458 51/ 00 l .2 1. 4868 5 2 200 l 4 1. .2646 24 201i 1 1 Ill. 7465 .54 1200 l 4 l. 5616 ii 200 3 4 1 48.0 ti .300 3 4 1 -17. ('1 .100 3 4 1 60. 5 t) 200 3 1 1 76. ti 6 .200 3 4 1 6i). 4 6 200 3 1 1 til. 1 ti 200 3 4 1 (i7. 7 8 ZUU 3 4 1 Tti. 4 8 IOU 3 1 1 44. SI 8 200 3 4 1 37. 5 8 200 3 2 1 15. 4 18 200 3 1 1 7 .1. 0 18 200 3 .2 1 13,0 18 .100 3 l 1 612. l .100 3 2 1 11. 5 5 .300 3 1 1 35. 1 '2 2 l 1 U. 2047 2-1 7.! L. J 1 U. 167" 1 In milligrams.

C 0 NC LU SION While the tests have shown the compositions to be effective in inhibiting 15% hydrochloric acid, they are also effective in inhibiting the various strength hydrochloric acid solutions up to its saturation solubility. They are similarly effective in inhibiting solutions of phosphoric, sulfuric and nitric acids.

What is claimed is:

1. An aqueous solution substantially non-corrosive to ferrous metals which consists essentially of a major proportion of an inorganic mineral acid from the group con sisting of hydrochloric, phosphoric, sulfuric, and nitric acid and from 0.001 to 2% by volume of a composition consisting essentially of:

(A) the Mannich reaction condensation product of one mole of a hydroabietyl amine with at least two moles of formaldehyde and at least two moles of an aldehyde containing from 2 to 6 carbon atoms and having at least one hydrogen atom on the carbon atom adjacent to the aldehydic carbonyl carbon atom, and (B) a monohydroxy acetylenic alcohol which contains from 3 to 12 carbon atoms: with the ratio of A to B being within the range of from 5:1 to 1:5.

2. The aqueous solution of an inorganic mineral acid as set forth in claim 1 where the mineral acid is hydrochloric.

3. The aqueous solution of an inorganic mineral acid as set forth in claim 1 wherein R and A are hydrogen and the acetylenic alcohol is 4-ethyl-l-octyn-3ol.

4. The aqueous solution of an inorganic mineral acid as set forth in claim 3 wherein the ratio of A to B is within the range of from 3:1 to 1:3.

5. The aqueous solution of an inorganic mineral acid as set forth in claim 4 wherein the ratio of A to B is within the range of 1:1 to 1:3.

6. A composition useful in inhibiting the corrosive tendencies of aqueous solutions of inorganic mineral acids from the group consisting of hydrochloric, phosphoric, sulfuric, and nitric acid, which consists essentially of from 10% to 30% by weight of a composition consisting essentially of:

(A) the Mannich reaction condensation product of one mole of hydroabietyl amine with at least two moles of formaldehyde and at least two moles of an aldehyde containing from 2 to 6 carbon atoms and having at least one hydrogen atom on the carbon atom adjacent to the aldehydic carbonyl carbon atom, and

(B) a monohydroxy acetylenic alcohol which contains from 3 to 12 carbon atoms;

with the ratio of A to B being within the range of from 5:1 to 1:5, 5-40% by weight of an oil soluble dispersant formed by reacting higher fatty acids and higher alkyl phenols with 5-50 moles of an alkoxide from the group consisting of ethylene oxide and propylene oxide; the balance being a hydrocarbon solvent for the above ingredients having a boiling point above C.

7. The composition of claim 6 wherein R and A are hydrogen and the acetylenic alcohol is 4-ethy1-1-octyn-3- 01; and wherein the oil soluble dispersant is an ethoxylated nonyl substituted phenol which contains from 5-50 moles of reacted ethylene oxide.

References Cited UNITED STATES PATENTS 2,975,125 3/1961 Saukaitis et a1. 2528.55 3,077,454 2/1963 Monroe et a1. 252-8.55 CX 3,107,221 10/1963 Harrison et a1. 252-148 3,113,113 12/1963 Marsh et a1. 252-392 3,230,173 1/1966 Spivack 252148 3,249,548 5/1966 Herman et a1. 252-146X MAYER WEINBLATT, Primary Examiner A. I. RADY, Assistant Examiner US. Cl. X.R.

*zg ggg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 585 l 36 Dated June 15 1971 Inventor-(s) James R. Stanford et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 5 Composition 12 should read as follows:

Gms. Composition I1 2O Nonyl phenol+12 moles ethylene oxide 15 Tall oil+l5 moles ethylene oxide l5 Aromatic solvent 40 Octynol 5 Aromatic solvent l5 4-ethyl--1 -octyn-3 -ol.

Column 6 Composition 19 should read as follows:

. Gms. Composition ll 30 Aromatic solvent 50 Octynol 1 0 Nonyl phenol+l2 moles ethylene oxide 10 4-ethyl-l octyn-3 -ol.

Signed and sealed this 11th day of January 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK J Attesting Officer Acting Commissioner of Patents 

